This project is aimed at studying the functional alterations in the microvasculature of animals under the condition of experimental diabetes mellitus. We have observed that the permeability of peritubular capillaries in the renal cortex to albumin increases, when the animals are rendered diabetic and no insulin replacement is provided; the specific method for carrying out these measurements has been worked out in our laboratory. During the forthcoming period of this research, activity will be aimed at determining 1. whether the development of microvascular alteration can be delayed or accelerated, 2. if alterations in lipid metabolism accompany the changes observed in microangiopathy, 3. whether large vessel walls are subject to deterioration together with the microvasculature and 4. if the question raised under (3) has connected with the capillary blood supply of the large vessel wall.